Propeller pitchometer



Pater-stead Ana. 29 i926.

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Fifi "I": 153

ii ass 2 RONALD C. DUNBAR, OF CHICAGO, ILLINOIS.

PROPELLEB PITGHOMETER.

Application filed June 16, 1920. Serial No. 389,457.

To all w/zom' it may concern:

Be it known that I, RONALD C. DUNBAR, a citizen of the United States, residing at Ul'iicagt'), in the county of Cook and State of Illinois, have invented certain new and use ful Improvements in Propeller Pitchometers, of which the following is a specification.

The present invention relates to pitcho netors for checking the edge and face ali nements of airplane propellers, and consists in the combinations and arrangements of elements hereinafter described and particir larly set forth in the accompanying claim.

The purpose of the invention to provide an improved apparatus of thls type by which propeller blades may be made accurately uniform in a simple and easily performed manner, and wherein the construction of apparatus will not require any high or special degree of skill for its use or understanding.

The invention is disclosed by way of illustration in the accompanying drawings, wherein Figure 1 is a top plan view of the pitchonieter applied to a propeller.

Figure 2, a side elevational view thereof; and

Figure 3 a transverse sectional view taken on the line 3-S of Figure 2.

Referring to the construction in further detail and wherein like reference characters indicate corresponding parts in the diiferent liguresshown, a designates a flat base or bed which may be the top of a suitable supporting structure such as a table or bench having thereon a center pin or post 5 and a block 6 for centering and supporting the propeller A, whose blades B are to have their edge and face alinements checked in accordance with the required specifications.

The instrument for checking the respective edge alinements consists of two similar devices to be used simultaneously and which are disposed in diagonal relation on the surface i of the support. Each of said edge checking devices, and hereinafter referred to as the edge alinement jig, consists of a strip 7 detachably secured on the supporting surface lby a pair of pins 8, or other means,

and adapted to be placed in position or removed at will. A plurality of graduated andequally spaced upright members 8 is mounted on each of the strips 7 and serve for simultaneously checking the correspondedges of both propeller blades as shown.

The device for checking the face alinement, and herein also referred to as a jig. consists of a relatively thin strip or bar 9, of any suitable material, and having on one end an enlarged portion 10 formed with an aperture providing a hub piece adapted to closely fit over the block 11 mounted on the pivot pin or axis 5 of the propeller; and on its opposite or outer end said bar 9 has a downwardly projecting piece 12 that serves as a support for holding the member 9 in true horizontal position, and also provides a gauge for checking the lengths of the propeller blades.

A member 13 having a curved'under edge let is secured to the bar 9 and piece 12 as shown, and serves to check the face or sun face alinement of the propeller blades. It will be understood, of course, that the memher 9 is adapted to be swung about the pivot pin 5 in order that the respective upper faces of the propeller blades may be checked to show any defects in the way of a rise or fall of the surfaces thereof, and said member 9 is suiiiciently offset from a true radius with respect to the axis 5 to place the inner edge 14 thereof on a true radial line with said axis which gives the measuring or correct gravity line of the propeller blades as shown.

It will therefore be seen from the foregoing that the corresponding edges of the propeller blades may be simultaneously checked for alinement by the use of the several graduated and equally spaced members 8*; and in a like manner the surfaces of the propeller blades may be checked for pitch, or to show defects in the way of rise and fall of the blade surfaces.

It is obvious that those skilled in the art may vary the details of construction and arrangement of parts without departing from the spirit of the invention, and it is therefore understood that the invention is not limited to such features except as may be required by the claim.

What is claimed as new is:

A propeller pitcliometer comprising a base, a center post for the propeller hub carried by the base, and a propeller surface checking arm journalecl on the center post,

the outer encl of which has a leg for bearing against the base and for checking the length RONALD C. DUNB AR. 

